1. Field of the Invention
The present invention is directed to a method for preserving fresh squeezed citrus and non-citrus fruit juices, fruit juice blends, fruit pulp, and dairy products and more particularly is directed to a thermal preservation process for aseptically packaging 100% pure fruit juices, juice blends, and fruit pulps, such that the packaged product has an extended shelf life of up to three years without refrigeration.
2. Description of the Prior Art
When fruits are harvested, microbiological and chemical changes occur which limit the time the fruit remains acceptable to the consumer and is safe for consumption. Since most of the postharvest changes in food lead to spoilage, various methods of food preservation are used to prolong the length of time for which the food, and especially fruit juices, retain quality add appeal.
In the days of simple farming communities, it was possible to live on locally grown fruits and vegetables and no highly organized methods of food preservation were necessary. In the modern world however, centers of world population are in towns and cities, often many miles from the main areas of food production. Thus, unless preserved, food deteriorates prior to reaching the consumer.
After harvesting, plant tissue is unable to prevent the attack of microorganisms such as bacteria, yeast, and molds, which break down the food structure and produce undesirable "off-flavors," discoloration, and odors. The number of organisms in an ounce of food can range from several hundred to twenty million or more and the organisms are capable of rapid multiplication, such that under certain conditions, their numbers can double every fifteen or twenty minutes.
Bacteria are minute microorganisms that are the most common cause of food spoilage. Generally, bacteria will either cause food spoilage, rendering the food unpleasant to eat, or in the case of pathogenic bacteria, such as Staphylococcus aureus or Clostridium botulinum, it will have far worse effects giving rise to food poisoning.
Food spoilage may also be caused by chemical substances known as enzymes which are always present in minute quantities in living materials. In fruit, enzymes are chemical catalysts which bring about the change of flavor and texture associated with ripening. Enzymes are also often responsible for the deterioration of fruits after harvesting, such as the browning of the cut surface of apples and pears caused by the oxidation of phenols in the enzyme phenolase. Enzymes can be rendered organically inactive by exposure to heat.
Thermal preservation techniques for rendering inactive bacteria and enzymes in fruit juices and citrus pulp typically rely on known, large scale, pasteurization techniques. Pasteurization is a mild heat treatment process, wherein a supply of food product is heated in stainless steel containers at temperatures normally less than 212.degree. F. (100.degree. C.). Although common pasteurization techniques destroy pathogenic organisms, they do not provide indefinite protection against microbiological spoilage.
Even an acidic product, such as fruit juice, requires protection from spoilage organisms such as acetobacter, whose growth can lead to cloudiness in the fruit juice product. Cloudiness in some citrus juice products is due to the presence of pectin, which occurs naturally in the fruit. If the natural pectolytic enzymes of the fruit are not destroyed, they degrade the pectin with the result that the juice becomes cloudy and often gels. Therefore, in order to destroy the pectolytic enzymes, most citrus juices are processed by flash pasteurizing in a plate heat exchanger at 203.degree. F. (95.degree. C.) for 30 seconds. However, while partially rendering enzymes organically inactive, this process degrades juice quality since the juice in contact with metallic heat exchanger elements is vastly overheated. Furthermore, the prior art methods have been found unsatisfactory for rendering the enzymes present in citrus and non-citrus fruit juices organically inactive or destroying bacteria and other pathogenic and non-pathogenic organisms.
As a result, certain fruit juices have not been made readily available to the consuming public due to the limited success of the prior art methods. For example, juices such as banana juice and pineapple juice are not found on store shelves packaged in a one hundred percent natural state. Oftentimes, the juice quality is compromised by the addition of various preservatives to maintain freshness and color.
Thus, there still exists a need for a thermal preservation process specifically designed for citrus and non-citrus fruit juices and fruit juice blends, citrus pulp, and dairy products, that provides aseptic packaging of these products in a one hundred percent natural state and results in an extended shelf life of up to three years without the need for refrigeration.